摘要
为系统揭示固流热耦合作用下裂隙花岗岩的非线性渗流特征及其主要控制参数演化规律,基于自主研制的高温高压三轴渗流试验装置,选取不同粗糙度(JRC)的单裂隙花岗岩试件,覆盖围压(1~20 MPa)、温度(25~90℃)和水压梯度(1~12 MPa/m)等多因素交互的工况进行试验研究。采用三维激光扫描技术与数字化重构手段精确获取裂隙面几何形貌,结合Forchheimer方程、非达西因子和临界水压梯度等指标,定量分析了体积流速、水力开度、导水系数等随围压和温度的演化机制。结果显示:单裂隙花岗岩在较高水压梯度或流速下显著偏离达西流态, Forchheimer方程拟合度高(R2>0.98),表明裂隙渗流具有明显的非线性特征;围压的升高会压密裂隙面并显著抑制渗透性能,粗糙度的增大加剧了闭合区形成并进一步削弱流体流动;温度的升高在低围压下会降低流体黏度并促进渗流速度,但在高围压下微裂纹扩展和局部表面磨损会部分抵消该增透作用;深部环境中裂隙非线性渗流普遍存在,随着水压梯度递增,导水系数由近似恒定转为幂指数衰减。研究成果可为高温高压场景下核废料地质处置库、地热开发和其他深部工程中裂隙渗透特性的安全评估与设计提供科学依据,并为后续多场耦合数值模拟与机理完善奠定重要试验基础。
To elucidate the nonlinear seepage characteristics and evolution of key controlling parameters of fractured granite under coupled thermo-hydro-mechanical conditions,fluid flow through fractured granited were investigated using a self-developed high-temperature and high-pressure triaxial seepage testing apparatus.Singlefractured granite specimens with varying roughness were selected and subjected to experiments under a range of confining pressures(1-20 MPa),temperatures(25-90℃),and pressure gradients(1-12 MPa/m)to simulate the interactive effects of multiple factors.The geometric morphology of the fracture surfaces was accurately captured using three-dimensional laser scanning technology and digital reconstruction techniques.In combination with the Forchheimer equation and indices,such as the non-Darcy factor and the critical pressure gradient,the evolution mechanisms of volumetric flow rate,hydraulic aperture and hydraulic conductivity with respect to confining pressure and temperature were quantitatively analyzed.The results show that the seepage behavior of single-fractured granite markedly deviates from Darcy flow under high pressure gradients or flow rates,with the Forchheimer equation yielding an excellent fit(R2>0.98),thereby demonstrating pronounced nonlinear characteristics.Furthermore,an increase in confining pressure leads to the compaction of fracture asperities,significantly reducing hydraulic aperture and consequently suppressing permeability,while an increase in fracture roughness exacerbates the formation of closed zones,further hindering fluid flow.Additionally,elevated temperatures reduce fluid viscosity and enhance seepage velocity under low confining pressures.However,under high confining pressures,the expansion of microcracks and local surface wear partially offset this permeability enhancement.Overall,the study confirms that nonlinear seepage is pervasive in deep geological environments,as evidenced by the transition of hydraulic conductivity from nearly constant behavior to power-law decay with increasing pressure gradients.These findings provide a robust scientific basis for the safety assessment and design of fractured permeability in nuclear waste disposal repositories,geothermal developments,and other deep underground engineering applications,as well as critical experimental support for subsequent multi-field coupling numerical simulations and mechanistic refinements.
作者
孟涛
杨翼嶂
冯淦
MENG Tao;YANG Yizhang;FENG Gan(College of Energy and Materials Engineering,Taiyuan University of Science and Technology,Taiyuan 030024,China;College of Water Resources and Hydropower,Sichuan University,Chengdu 610065,China)
出处
《采矿与岩层控制工程学报》
北大核心
2025年第6期107-121,共15页
Journal of Mining and Strata Control Engineering
基金
国家自然科学基金资助项目(52474080,52374099)
四川省自然科学基金区域创新合作资助项目(2025YFHZ0323)。
